“Specialists expect nothing less than a technological revolution from quantum computers, which they hope will soon allow them to solve problems that are currently too complex for classical supercomputers. Commonly discussed areas of application include data encryption and decryption, as well as special problems in the fields of physics, quantum chemistry and materials research. But when it comes to concrete questions that only quantum computers can answer, experts have remained relatively vague. Researchers from ETH Zurich and Microsoft Research are now presenting a specific application for the first time in the scientific journal PNAS: evaluating a complex chemical reaction. Based on this example, the scientists show that quantum computers can indeed deliver scientifically relevant results. A team of researchers led by ETH professors Markus Reiher and Matthias Troyer used simulations to demonstrate how a complex chemical reaction could be calculated with the help of a quantum computer. To accomplish this, the quantum computer must be of a “moderate size”, says Matthias Troyer, who is Professor for Computational Physics at ETH Zurich and currently works for Microsoft. The mechanism of this reaction would be nearly impossible to assess with a classical supercomputer alone – especially if the results are to be sufficiently precise.”